Inheritance

When a new class created from an existing class. Such that new class inherits attributes and behavior of existing class called Inheritance.

If you want more information on Inheritance in JavaScript. Look at the Mozilla Developer Network article: Inheritance and the prototype chain

Example: In this example we have two classes Employee and Manager as shown below.

class Employee {
    private _name : string;
    constructor(name:string){
       this._name = name;
    }
}
//To create a subclass we use extends
class Manager extends Employee {
    constructor(name:string){
       // To call the base class member we use super
       super(name);
    }
}

We are using super() to call the base class constructor. In the above example we are passing name into our base class to update the _name field in base class.

Also note that we cannot call a super() method if we haven't extended our class from any base class.